Question

How many Sulfur atoms are in 0.42 mol S?

Answer 1

If I have half a dozen sulfur atoms; clearly I have 6 sulfur atoms. If I have 0.42 mol of sulfur there are `0.42 xx N_A` sulfur atoms, where `N_A =` Avogadro's number.

Explanation:

The mole is simply a number, admittedly a very large number: `N_A = 6.022 xx 10^(23)`. So, in fact I have `0.42 xx N_A` sulfur atoms.

To expand, Avogadro's number, `N_A`, is simply the link between the micro world of atoms and molecules, with the macro world of grams and kilograms. If I have a mass of `32.06` `g` of sulfur, which I can easily weigh out on a bench, I know, to a very good approximation, that I have `6.022 xx 10^(23)` sulfur atoms (these may be individual atoms or they may be part of `S_8` rings - the number of sulfur atoms is determined directly!)